Antenna



Sept. 1, 1931.

N. E. LINDENBLAD ANTENNA Filed Oct. 28, 1927 2 Sheets-Sheet 1 u a: iF

INVENTOR s E. LINDENBLAD A ORNEY p 1931; N. E. LINDENBLAD 1,821,387

ANTENNA Filed Oct. 28, 1927 2 Sheets-Sheet 2 74 TRAf/JM/TTFR INVENTOR NILS. E. LINDENBLAD yn/1%, (MG/W ATTORNEY Patented Sept. 1 1931 8! F LIN EN??? 9 ee KY eelmye 193 e e e iee we BAQPIQ eeeeeeemy 9 AMEB F e eeeeq eele i eF' PeWe E' ANTENNA Application filed Octuber 28, 1927. Serial No. 22%05.

lhi i yentiee ele e to eet eiez end neye per ieyl rly e9 liree' iye eee ee e' he exfiepei y ele ie idin l e r m m e s i erfle eefineete ieties f t e.

1 iy ly-eLoee ly tegeiher eee th edie ieil- T is n e nee f the end-0n type.

Th re se h b en su e t d end Put int se diree e tenne ef thebm'e ide ype whe ein 5e pl ra ity of rad a r er le et d nermelly 9f t e ect of eeemi eie ende e xeited eep eeially by of e emplex eyet me eymmetrieel y mee hed eede l ne e, v r

It is e p ry ebjeet my in ex biente mpxey s e enten e- Th nd-en e tenl first ment oned is mpl n etri ire be I hey impreyed i? eperetie Th Jer ed-v ei e an nna. .eelyerie r fi iequ xee e e z plex sl lr u e ylli h I heye grea y implifie by x iting the-feren e yediete e by e p ir of linear ede m mber mush as. i the ease ef t e end-e1 antenna, u arranged t ed ene gy e? e pere infinite eleeity It is el er hat f r an enna e th type un er eeneidere ien they mus be, accur te ent el the e ei y of en y transf r along th d r membee f r th ewhet dete min s t lee ye Phase r le iene in he; ndiv dua ad ate-re wh ch mak up the nt lln The eeity en ree m eien ine m y e determin d y ed'il ei 'll nt 9f he el tiv du a e. nd pee tenee eher- ,v line, bu in the l ase f an ante na he imefi en is eempl leeefied by th xis e c .Qf e pewe l .epe-ee yyeve eg i redited energy h eh re ete 111 911" Phe l ne- 'l er foxe in ord r to, be ab e to govern l ke ve eity i is nt l eMh yy ve n he.

feede memb rbe net pn demix ei d ever y the e e/y n epeee, end ov et ein hieli ne .Qbj t f my ny netieln, which WQm-I relish y piec nge eeder members releend .eeupling he rea di zqso r s fcre nsversely and externally to the feeder" membersyr athef. than bfiwn them. ,1 this m th reeee e fromehe e ve'rsals' does not have to cross the feeder membeIS, and meanwhile the ea pecitenee of the line fela tive 't'o that Of the rediatoi'rs i'si'inpre'ased.

The effect of the s paee Wave on the feeder mel nbel s is fi l 'rthe yfliecluced by r e dujeing the emqqm -pf energy tapped fleem the-fedei mepr1b e,1 s by eheindiyidu al radiators. Thie reduction 10f atfiem iatgiofl bebb taine d in S ere wey fer i a' y d e eg he. length of the .ieditdrsi, so sis 130 decreae h ir epe ten e'; by d r ee t e Spec; igg and inerleas ing' the 'size'of the feeder mem ere in l ie e ehe r v p e tance, or by using l imifcipg feact anee, preferably small cgnden sers; in 's ei'ie syvi'ph the edi ter e e en; t eee ee' i ie i eb y y e m th e e between e ee i e may ept as 51 refiec't'idn' poin Tb'overcyome this is figrtlier bbject' of my invention which I fulfill'by em lo ng, whe e messgxyy, e gl egltep number off-reinsye rsle yeloci'ty control ind1e1jancee thjai jshefe ere tga rg sy epse rediagopsf 4' e For a de sifed degree of dineqbiyity there is a minimum Ieng thef memmeamnm sysfee m- In thee e e 'ihe endel entenna 161's "clesiiablwhetfth a'fiteima't o ar mt o ithdrew} f e er y r m t e fee er membefebeeuqh th at the enefgy t-liereiil is bro ughgtq zeipjet me end of the-antenna. If. theegt zemmfciop is jtpb smell theliei$ en e y Jaef? ey e-t h nd o 'fih li Whieh,

n e s ebe ed f f refie fiee e e' ee fie ia n meet i h F eni ergy eeeee. he fee eeflee' ed rg is ne y neeem eted in e e eppeeite'e ee s ee yhi lee of course, spoils the radiation pattern oftion from the transversals does not have to the antenna, and is Wasted. If the attenuation is too great the energy radiated by the first portion of the antenna induces energy back into the latter portion of the antenna and standing waves may result. In any event, when the attenuation is too great only the first portion of the antenna is effective, and therefore the requirement of minimum length of extensive system is no longer fulfilled. It is therefore clear that accurate control of attenuation, as well as of velocity, is required, and to meet this requirement is a further object of my invention. For this the expedients already suggested for limiting the withdrawal of energy by the radiators are perfectly suited, inasmuch as the natural rate of attenuation, in general, is too great.

In the case of the end-on antenna there is exceedingly sharp directivity not only in azimuth but also in elevation. This is desirable because it is economical of energy, but it leads to the disadvantage that the wave, if transmitted horizontally, lacks elevated components, which may reduce the distance of communication. It is a still further object of my invention to overcome this difficulty, which I do by pointing the an tenna upwards, that is, I position the successive radiators on a line which points toward the receiver, in azimuth, and above the horizontal, in elevation.

This is helpful but not a certain solution of the difficulty, for the space wave obtained is sharply directively transmitted and may not strike a favorable reflection or refraction portion of the Heaviside layer. To improve this condition I employ a plurality of end-on antennae having differing directivities in elevation, and I energize these successively and cyclically in order to wobble the transmitted beam in elevation.

My invention is further described and further claimed in my copending companion application, Serial Number 229, lO7,filedon even date herewith, and in the following specification, which is accompanied by drawings in which Figure l is a fragment and explanatory of one form of antenna,

Figure 2 is a fragment and explanatory of another form of antenna;

Figure 3 is a radiation pattern;

Figure 4 indicates an elevated end-on antenna; and

Figure 5 represents an arrangement for directivity Wobble in elevation.

Referring to Figure 1 it is seen that the feeder members 2 are located relatively closely together, and that the radiators 4 and 14: are coupled transversely and externally to the feeder members, rather than between them. This change isexceedingly important for it results in that the radiacross and interlink with the feeder members. It also results in that because the feeder members are close together the region between them contains potential and magnetic lines of force which are normal, rather than curved, as seems to be the case when the feeder members are far apart, owing to the lag caused by the lower velocityof the lines of force in space. It

also increases the capacitance of the feeder members, thereby helping the energy therein to predominate over the space wave.

To further increase the capacitance and decrease the surge impedance of the feeder members they may be enlarged in cross section, or several conductors may be used in parallel, as has been indicated in Figure 1. This procedure is beneficial, and if carried sufficiently far, may alone be used to obtain feed line domination and successful velocity control. However, to solve the problem entirely by this expedient is structurally inconvenient and expensive, and it is much better to use a transmission line of more ordinary dimensions, and to limit the attenuation by other means.

In Figure l the radiators 4 and 14 have been shortened, physically, thus reducing their capacitance and their relative energy withdrawal. They may be considered as having been lengthened electrically so as to again bring them in tune by a fictitious inductance 6, which resonates with the natural capacitance of the radiator 8.

For velocity control transverse inductances are used. The velocity-reactance curve is similar to a curve of tangents, and, in the range in which I choose to Work, a larger inductance connected across the'line causesa smaller resultant velocity. A total absence of transverse connection is a case of infinite inductance, and therefore low velocity. To increase the velocity transverse inductances of finite size are connected across the line, and these may be decreased or increased in magnitude according as it is desired to increase or decrease the apparent velocity of energy flow on the line. Bv suitably choosing the inductances the velocity may be increased to apparent infinite velocity. The word apparent is inserted because it is impossible to really cause energy to flow along a line at an infinite velocity, in the transient state, but it is possible to have all parts of the line fluctuating cophasially immediately after the transient state, which is apparent infinite velocity. Because of the nature of a curve 'of tangents, if the inductance is further decreased the velocity swings from infinity in one algebraic sense to infinity in the opposite algebraic sense, and thereafter becomes finite in decreasing values. This is pointed out because it explains Why the adjustment for ctually infinite y leci ity is more critical than the adjustment for light elocity, as n an end-n ante na. In atten end-0n type of an enna may he succes fully used over a modera e" band. of transmission frequencies.

In Figure 1 the'fict' tieus may be considered a yeloci y c n rol in u tance of proper magnitude to. prodnce the desired velocity in the'feedcr members. It is clear that the fictitious parallel inductance 6 and lO. may be replacedby. anequivalent inductance of lower reactance, such a the.

inductance 12 shown in series with radiator.

14. The radiator 14:, loaded by the inductance 12, is apparently detuned with respect to the. transmission frequency.

The inductance 16 is a velocity control inductance located intermediate the radiators igand 14, and serves to improve the action of the feeder. members as. a transmis: sion line,esp,ecially in cases Where the radiaters re pa ed at. relatively greater inte v'als.

- Attention is now directed to Eigure 2, in which there are feeder members 22, which may. take the form of a copper strip, to which there are coupled transyerse radiators 24- and 34, through small series condensers S6. .The equivalent circuit consists of a fictitious'tuninginductance' 26, the, natural capacitance of the radiators 2.8, and the series condensers .36. The reactance of the capacitiyebranch is governed mostly by thatof the small series condensers; By

coupling through these limiting reactances theicapitance .of the radiatorssis. lowered, and therefore they need not be "physically decreased in length, and preferably may be increased. Decreasing the capitance of the radiators. .byshortening. them lessens their radiation. resistance. 'By the" expedient adopted in Figure 2 the radiation resistance notonlyneed not be decreased but actually may. be increased, and meanwhile the capacitance may be made any Value desired. Increased radiation resistance, from' a simpler aspect, means merely. that the transversal is morev efiiciently a radiator, which might be predicted from its greaterlength. I

-' As in Figure 1 there is a fictitious velocity control 'inductance '3O, and the parallel ihductances 26 and 8Qmay bereplaced by asingle inductance" 32'. "Also, if desired, additional velocity control inductances may be used. c

Itis to. be understood that the. various features so far pointed out are equally ap -i -plicable to end-on and broadside antenna systems. In its most general aspect my invention makes these systems. alike, at

least, in fundamentals. "To .explain this more clearly attention is directed to Figure 3,.in which an extensive. antenna system is inductance .10.:

i th radiators. along. theantean AB. arexeitedp phasi lly they radiate normally of the antenna, Whereas'if they areexcited t phase di placements qual those of the ve in pac .the an enn .v propagates. elnergyielpng i s length, and ifthe radias. tor are exc ted phase. di pl cemen s greater than those of the Wave in spa e the antenna propagates energy in'intermediate. direc i ns- 1 I excite the. rad tors from simple linear eeder lnembersrand obtain the desired phase disp acements by causingthe' energy flow on the-feeder members to dominate the space. wave. and. by then controllingthe ves locity of energy fiowalong the feeder mem here to. be th t? desired. It is clear that for end-on propogation the yelocity should be that of light, for broadside propagationthe velocity. should be infinite, and for intermedi-, ate directions the velocity should be intermediate. infinite velocity and that of light.

th f ii rgy along the antenna n the direction tronih to; B at the Velocity nten a AB f opposite phase. which pens tralize onef moths..-

Itthe y oci y of flow long he feed r member rom. A tov B. isinereas d the radiaio pattern 0 sp t up in thep terns E an F, and ref ec ion w l ca se additional lobes G and H. f If the telocity is madei fin te. the adi ejnpa terns a e; J an whi hare equal- The. reas n i201: thi i hat apparen infinite v locity prod ced by aus ng a standing were of' infinite leng h: To. ma ai he teady tate ull refl ction d iittlea en tion are desired. In broadside piiQpegation, he lobe K i the merger of th lob F an and ther fo refle tion no at en,- desite le- For un direetiv Peerage-ties ad: ditie aeten e may used t ppp se a d. re e it thelehel- 4' i feeder members. i

" In Figure. 4 there is indicated an end-on antenna comprising feeder members 42 which excite transverse radiators 44 supported between supporting lines 46. For the sake of simplicity the series reactances have been omitted. The lines 46 are attached atone end to a mast52.- The other ends of the lines 46 are passed over pulleys 54 attachedat a different altitude to a mast 56. With this arrangement the successive radiators are positioned on a line which points toward the receiver, in azimuth, and above horizontal a desired amount, in elevation.

In Figure 5 there are shown two complete end-on antennae 60 and which are supported between masts 54 and 56 at differing angles in elevation. The antenna are fed by transmission lines 68 and 70, which lead to a distributor means 72, to which transmission energy is fed from a source 74. The distributor serves to supply the energy to the antennae successively and cyclically, so that the directivity in elevation is-wobbled. For a more detailed description of a distributor suitable for wobbling reference is made to my copending application, Serial N 0. 213,566 filed August 17, 1927.

The end-on antennae may be suspended so that the transverse radiators are either Vertical, horizontal, or biased. For wobbled transmission more than two antennae may be employed.

I claim 1. Apparatus for propagating high frequency energy which comprises a plurality of spaced radiators spaced in a phase relationship when energized-substantially equal to that of a wave in space, and positioned so that the successive radiators are on a line which points towards the receiver, in azimuth, and above the horizontal, in elevation. v

- 2. An end-on extensive antenna system comprising relatively closely spaced feeder members extending in the direction of transmission, and a plurality of radiators transversely and externally coupled thereto, said feeder members being linear throughout their length.

3. An end-on extensive antenna system comprising relatively closely spaced feeder members of relatively large cross section ex tending in the direction of transmission, and a plurality of radiators transversely and externally coupled thereto.

4. An end-on extensive antenna system comprising relatively closely spaced feeder members of low surge impedance extending in the direction of transmission, and a plurality of radiators of low capacitance transversely and externally coupled thereto.

5. An end-on extensive antenna system comprising feeder members extending in the direction of transmission, and a plurality of radiators transversely and externally c0upled thereto'through limiting series re actances.

6. An end-on extensive antenna system comprising feeder members extending in the direction of transmission and a plurality of radiators transversely and externally coupled thereto through small series condensers.

7 An end-one extensive antenna system comprising feeder members extending in the direction of transmission, a plurality of radiators transversely andexternally coupled thereto, anda plurality of velocity control inductances transversely and internally coupled thereto.

8. An end-on. extensive antenna system comprising feeder members extending in the direction of transmission, a plurality of radiators transversely and externally coupled thereto, and a greater number of velocity control inductances. transversely and internally coupled thereto;

9. An end-on extensive antenna system radiators transversely and externally cou-* pled thereto, and a plurality of velocity control and tuning inductances transversely,

and internally coupled thereto. 1

11. An end-on extensive antenna system comprising feeder members extending in the direction of transmission, in azimuth, and abovehorizontal, in elevation, a plurality of radiators transversely and externally coupled thereto, and a plurality of velocity control and tuning inductances transversely and internally coupled thereto. 12. In the operation of an end-on extensive antenna comprising linear feeder members extending in the direction of transmission and transverse radiators coupled thereto, the method which includes the step of conducting a relatively increased amount of energy through the feeder members, and absorbing a relatively decreased amount of energy in each radiator, so as to cause the,

energy wave in the feeder members to predominate over the space wave traversing the antenna.

13. An extensive transmitting antenna system comprising feeder members and a plurality ofradiators transversely and externally coupled thereto through series condensers, said feeder members being conductive and linearv throughout their length.

14. A directive antenna system for propagating electromagnetic Wave energy comprising a pair of closely spaced conductors substantially linear throughout their length, a plurality of radiators parallel to each other arranged in one plane, a condenser in series with each of said radiators for coupling each of the radiators to one of said conductors; another plurality of radiators each of the radiators of said second plurality being parallel to each other and arranged in the same plane as the plane of said first mentioned plurality of radiators, and a condenser in series with each of the radiators of said last mentioned plurality of radiators for coupling each of said last mentioned plurality of radiators to said other linear conductor.

NILS E. LINDENBLAD. 

